Defender was one of the most important titles of the Golden Age of Video Arcade Games, selling over 55,000 units to become the company's best selling game and one of the highest-grossing arcade games ever. Praise among critics focused on the game's audio-visuals and gameplay. It is frequently listed as one of Jarvis' best contributions to the video game industry, as well as one of the most difficult video games. Though not the first game to scroll horizontally, it created the genre of purely horizontal scrolling shooters. It inspired the development of other games and was followed by sequels and many imitations.

There were many ports to contemporary systems, most of them by either Atari, Inc. or its software label for non-Atari platforms, Atarisoft.

The starship (upper right) flies along the planet surface to defeat enemies and protect astronauts. The status bar at the top depicts the remaining ships and special weapons, number of points earned, and a miniature map of the stage.

Defender is a two-dimensional side-scrolling shooting game set on the surface of an unnamed planet. The player controls a space ship as it navigates the terrain, flying either to the left or right. A joystick controls the ship's elevation, and five buttons control its horizontal direction and weapons. The object is to destroy alien invaders, while protecting astronauts on the landscape from abduction. Humans that are abducted return as mutants that attack the ship. Defeating the aliens allows the player to progress to the next level. Failing to protect the astronauts, however, causes the planet to explode and the level to become populated with mutants. Surviving the waves of mutants results in the restoration of the planet. Players are allotted three ships to progress through the game and are able to earn more by reaching certain scoring benchmarks. A ship is lost if it is hit by an enemy, or hit by an enemy projectile, or if a hyperspace jump goes wrong (as they randomly do). After exhausting all ships, the game ends.[2][3][4][5]

Eugene Jarvis, a pinball programmer at the time, headed development of Defender.

Defender was Williams Electronics' first attempt at developing a new video game; the company's earlier game was a Pong clone.[2] The popularity of coin-operated arcade games in 1979 spurred the company to shift its focus from pinball games to arcade games.[6] The company chose Eugene Jarvis, who had a successful record of Williams pinball games, to head development.[2]Larry DeMar, Sam Dicker, and Paul Dussault assisted Jarvis.[7] At the time, Williams had a small staff and the management was unfamiliar with technology used for its electronic games. As a result, the staff was afforded a large amount of creative freedom.[6]

Space was a popular setting for video games at the time, and Jarvis felt the abstract setting would help obscure simple graphics that lacked realism.[2] Initially, Jarvis spent 3–4 months developing color variations of Taito's Space Invaders and Atari's Asteroids.[8] First inspired by Space Invaders, he created a similar game with new gameplay mechanics. After spending a few weeks on the design, however, the team abandoned the idea, believing it lacked enjoyment. Development then shifted to emulating Atari's Asteroids, but hardware differences between Asteroids and Defender's proposed specifications were problematic. Asteroids displays vector graphics on a special monitor, while the staff planned to use pixel graphics on a conventional monitor. The team experimented with recreating the game with pixel graphics, but also abandoned it because they felt the gameplay lacked enjoyment and visual appeal.[9]

Believing their first attempts to be too derivative, the developers held brain storming sessions. During a session, they agreed that one of Asteroids's favorable elements was its wrapping effect.[Note 1][9] They felt a game that allowed the player to fly off the screen would be exciting, and decided to create a game world larger than the screen displayed. The game's environment was made longer than the screen, with the visible area scrolling horizontally.[2][9] Expanding on the idea, they envisioned a version of Space Invaders rotated 90 degrees. By changing the orientation of Space Invaders' design, the ship moved up and down while flying horizontally. Large asteroids, an element from Asteroids, were then added to the game world, but were later removed because the staff felt it lacked enjoyment.[9] Jarvis intended the screen to scroll only from left to right; fellow Williams employee Steve Ritchie, however, convinced him the game should be able to scroll in either direction.[2][9]

I had this whole justification for why you were there and what you were doing. A lot of games fall short. They just put you there, and all of a sudden you're beating people up and you start to wonder. "Why am I beating these people up?" There was actually an old TV show called The Defenders about attorneys back in the 1960s, and I kind of liked that show. You know, if you're defending something, you're being attacked, and you can do whatever you wanted.

After six months of development, the team felt the game had not made enough progress. They examined other games and concluded that survival was a necessary component to implement. To achieve this, they devised enemies to present a threat, the first of which was the "Lander".[9] Jarvis enjoyed violent, action entertainment, and wanted the game to have those elements. However, he felt the action should have a reasonable objective. Inspired by the 1960s television show The Defenders, Jarvis titled the game Defender, reasoning that the title helped justify the violence.[2] He added astronauts to expand on the space theme and give players something to defend while they shot enemies.[2][9] The element of flying over a planetscape was added after a brainstorming session between Jarvis and Ritchie.[10] The landscape is depicted as a line only a pixel wide, primarily because the hardware was not powerful enough to generate anything more detailed.[9]

By July, development was behind schedule and Jarvis's superior began to pressure him to finish the game in time for an upcoming trade show, the AMOA, in September. Jarvis spent several weeks creating the astronauts, which his boss felt should be omitted if the process didn't speed up. The pressure frustrated him to the point he considered resigning. Around that time, a new programmer named Sam Dicker was hired.[2] He assisted programming the game and added visual and audio effects.[2][9] For example, Dicker implemented a particle effect algorithm to generate unique explosions for destroyed enemies.[9] The new elements re-invigorated Jarvis, who felt the project began to show promise.[2]

Development then shifted focus to the enemies. Landers were given the ability to capture humans, and a new enemy was devised from the mechanic: "Mutants", captured humans that had turned hostile. The Mutants added a rescue element to the game that Jarvis believed made it more interesting to players and encouraged them to continue playing. The element of making a "comeback" from a dire situation was applied to the planet as well. Jarvis felt it mimicked the ups and downs of real life. "Bombers", enemies which release floating bombs on the screen, were added next. More enemies were added to create different gameplay elements. "Swarmers" and "Pods" were designed to attack the spaceship as opposed to the astronauts. "Baiters" were included to add pressure to the player by preventing them from lingering. The enemies quickly follow the spaceship to collide with it, and were based on a similar enemy in Asteroids.[9]

By September, the game was still unfinished, and almost every Williams programmer assisted in meeting the deadline for the AMOA trade show.[2][11] The evening before the trade show, the arcade cabinets were delivered for display.[8] The developers, however, forgot to create an attract mode—an automated sequence designed to entice an audience to play—for the game, and began working on it that night. Early the next morning, the team created the final EPROM chips for the mode and installed them in cabinets. The chips, however, did not work and the designers made additional attempts to correct the problem. Once the attract mode was operational, Jarvis and the team returned to their homes to prepare for the show.[5] After the show, the developers expanded the game to allow users to play indefinitely. The display model featured five levels, which the team felt was more than enough because of the game's difficulty. Most Williams employees could not progress past the third level and Jarvis's score of 60,000 points seemed unbeatable to them. The developers decided it was best to be prepared for players that might exceed their expectations and added more levels that repeated.[8]

Development started by focusing on the game's hardware. The staff first debated what type of monitor to use: black and white or color. They reasoned that using advanced technology would better establish them as good designers and chose a color monitor. The developers estimated that the game would require 4 colors, but instead chose hardware that could display each pixel in 16 colors. At the time, the designers believed that was more than they would ever need for a game.[2] The monitor's resolution is 320×256, an expansion from the then industry standard of 256×256. The staff believed that the wider screen provided a better aspect ratio and would improve the game's presentation.[9] Video games at the time relied on hardware to animate graphics, but the developers decided to use software to handle animation and programmed the game in assembly language.[6][9] The switch allowed them to display more on-screen objects at a lower cost.[9]

The game's control scheme uses a two-way joystick and five buttons. Jarvis designed the controls to emulate both Space Invaders and Asteroids simultaneously. The player's left hand manipulates the joystick similar to Space Invaders and the right hand pushes buttons similar to Asteroids. The button functions also use a similar layout to Asteroids, with the button to shoot projectiles and accelerate on the far right and left, respectively. Jarvis reasoned that players were accustomed to the control schemes of past games, and felt altering past designs would prove difficult for them.[9]

Initially, the game was slow to gain popularity.[3]Defender did not attract much attention at the 1980 AMOA show.[2][7][11] In retrospect, Jarvis believed many passersby were intimidated by its complexity. The game, however, was well received in arcades, and crowds gathered around the cabinet during its first nights of play testing.[5] The success spurred Williams to release a cocktail version as well.[8]Defender eventually became Williams' best selling arcade game, with over 55,000 units sold worldwide.[2][8][13] By 2004, the game was a popular collector's item; the upright cabinets were common, while the cocktail models were more rare.[14] Since its release, it has become one of the highest grossing arcade games ever, earning over US$1 billion.[11][15] Williams employee Larry Demar was surprised at the game's popularity, stating that it was the only game he'd seen able to earn that quantity of quarters.[2] Six months after its release, the game was one of the top earners in the United States video game industry.[8] Mark Stearny of JoyStik magazine called Defender the most successful game in 1981, commenting that it outperformed Pac-Man.[4]

The game garnered praise for its graphics, audio, and gameplay features. GameSpy's David Cuciz lauded Defender's challenging gameplay, commenting that it is representative of what other games should be. He described the graphics as "beautiful", citing the varied sprites and flashing explosions.[11] Matt Barton and Bill Loguidice of Gamasutra stated the audio-visuals and gameplay's depth balanced the excessive difficulty. They praised the game's "catch and rescue" feature, as well as the minimap.[7] Cuciz also praised the minimap, stating that the game is impossible without it and that it allows players to plan strategies.[11] Author John Sellers praised the audio-visuals and the connection between the game's plot and gameplay.[5] At the time of its release, Stan Jarocki, director of marketing at then competitor Midway Manufacturing,[Note 2] described the game as "amazing".[8] In 2008, Guinness World Records listed it as the number six arcade game in technical, creative, and cultural impact.[3] That same year, Retro Gamer rated the game number ten on their list of "Top 25 Arcade Games", citing it as a technical achievement and a difficult title with addictive gameplay.[16] Also in 2008, Edge ranked Defender the sixth best game from the 1980s. The editors described its design as very "elegant" despite a lack of narrative and characters.[17]

Defender is often described as one of the most difficult games in the industry. Softline in 1983 wrote that it "remains one of the hardest arcade games ever developed. Initial attempts lasting less than ten seconds are not uncommon for novices".[18] GameDaily in 2009 rated Defender the ninth most difficult game, citing the attack and rescue gameplay.[19] Author Steven L. Kent called it "one of the toughest games in arcade history". He also stated that novice players typically are able to play only a few seconds, and that enthusiasts saw proficiency at the game as a "badge of honor".[2] David Cuciz echoed similar comments.[11] Sellers described Defender's difficulty as "humbling", saying that few could play it with proficiency. He further stated, however, that players would continue to play despite the difficulty.[5] Author David Ellis attributes the game's success to its challenging design.[13] Its difficulty is often attributed to its complex control scheme.[3][5][7]Edge magazine called Defender "one of the most difficult-to-master" games, describing its controls as "daunting".[17]Retro Gamer writer Craig Grannell called the game and controls "ruthless" and "complex" respectively.[9]

In 1983 Softline readers named the Atari 8-bit version fifth on the magazine's Top Thirty list of Atari programs by popularity.[20] The magazine was more critical, however, stating that "The game's appeal does not justify its unreasonable cost" of being shipped on cartridge.[18]

Players have competed to obtain the highest score at the game and the longest play time on a single credit.[5][21][22] Competitive playing for the longest play time was popularized by Mario Suarez from Atlantic City, who played Defender for over 21 and half hours in 1982 at the Claridge Casino Hotel in Atlantic City.[5][23] It was authenticated by the facility and the many witnesses that watched along with the press of Atlantic City; the media attention spurred other players to attempt the same feat.[5] Expert players exploited software bugs to extend the length of their play time. Defender was the focus of the first Twin Galaxies video game contest. Players in 32 cities simultaneously competed the weekend of April 3–4, 1982. Rick Smith was the victor with a score of 33,013,200 which took 38 hours.[24][25] One bug, related to how the game keeps track of scoring, allows players to earn a large number of "extra lives". Players can then use the extra lives to leave the game unattended while they rest.[8] Other bugs allow the ship to avoid damage from the enemies, also prolonging the length of play.[9]

Professor Jim Whitehead listed Defender as the first horizontally scrolling shooting game, and describes it as a breakthrough title for its use of full 2D motion, multiple goals, and complex gameplay that provides players with several methods to play.[26] James Hague of Dadgum Games called Defender a landmark title from the 1980s.[6] Stearny said that the game's use of scrolling helped remove design limitations associated with the screen.[4] Cuciz stated that Defender's use of scrolling introduce the "first true 'gaming environment'". He further said that though the game's minimap feature had been introduced before, Defender integrated it into the gameplay in a more essential manner.[11] Stearny described it as the most important space game in the early 1980s. He commented that its realism and technological advances pushed developers to create more popular games, citing Gorf and Phoenix as examples.[4] Vince listed the game as a classic title that introduced new technology, specifically scrolling.[27] Ellis stated that prior to Defender, companies designed video games to have a balanced challenge. They believed games should be easy enough to attract players, but difficult enough to limit play time to a few minutes; anything too challenging would dissuade players.[13] Loguidice and Barton commented that Defender's success, along with Robotron: 2084, illustrated that video game enthusiasts were ready for more difficult games, which spurred developers to create more complex game designs.[7][28]

Jarvis's contributions to the game's development are often cited among his accolades.[29][30] Author John Vince considered him as one of the originators of "high-action" and "reflex-based" arcade games, citing Defender's gameplay among other games designed by Jarvis.[27] Ellis stated that Jarvis established himself as an early "hard-core" designer with Defender.[13] In 2007, IGN listed Eugene Jarvis as a top game designer whose titles (Defender, Robotron: 2084 and Smash TV) have influenced the video game industry.[30] Barton and Loguidice stated that the game helped establish Williams and Jarvis as key figures in the arcade game industry.[7] Sellers echoed similar comments.[5] After the success of Defender, Williams expanded their business by building a new facility and hired more employees. Before the expansion, Jarvis could work in isolation. But the influx of people created an environment he was unhappy with. He left Williams along with DeMar to found their own development company, Vid Kidz.[6] The company served as a consulting firm to Williams and developed two games for them.[7]

A 2002 sequel by the same name features gameplay elements similar to the original, but with three-dimensional graphics.

The success of Defender prompted Williams to approach Vid Kidz, who originally wanted to create a new game. DeMar, however, suggested creating an enhanced version of Defender to meet Williams' four-month deadline. Vid Kidz titled the game Stargate, and developed it as a sequel to Defender. It features new elements and improved the original's performance.[6] Some home ports of Stargate were released under the title Defender II for trademark purposes.

Williams released a Defender-themed pinball machine in 1982.[8][31] It has many elements from the original game: sound effects, enemies, waves, and weapons. Williams produced fewer than 400 units, which have become rare machines.[31]

Midway's 1991 Strike Force is an arcade update to Defender in the same way that Smash TV is an update to Robotron: 2084. Jarvis and DeMar assisted with the game, which was programmed by Todd Allen and Eric Pribyl. The game was not widely distributed.

Home games that copied Defender's design include Gorgon for the Apple II (1981), Repton for the Apple II (1983), Defender 64 for the Commodore 64 (1983), Dropzone for the Atari 8-bit family (1984), Guardian for the Commodore 64 (1984), and Planetoid for the BBC Micro (1984).

Video game designer Jeff Minter based several of his games on Defender's design.[32]

Other games built upon the design elements of Defender, especially protecting people or vehicles along the ground in a horizontally scrolling world, such as Protector II for the Atari 8-bit family (1982), Chopper Command for the Atari 2600 (1982), and Choplifter for the Apple II (1982).